Diffusion characteristics of subcortical structures in patients with subcortical ischemic vascular disease and its correlation to cognitive function / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the diffusion-tensor imaging (DTI) characteristics of normal-appearing white matter (NAWM) and normal-appearing gray matter (NAGM) on conventional magnetic resonance imaging (MRI) in patients with subcortical ischemic vascular disease (SIVD) and examine the relation of such features with the general cognitive function of the patients.</p><p><b>METHODS</b>DTI was performed in 46 SIVD patients and 34 age-matched control subjects with normal MRI findings. The apprarent diffusion coeeficient (ADC) and fractional anisotropy (FA) were measured within the regions of white matter lesions (WMLs), NAWM and NAGM. All the subjects were examined by neurologists with MMSE and clinical neurologic examination.</p><p><b>RESULTS</b>Compared with normal controls, SIVD subjects showed increased ADC values in the subcortical NAGM and NAWM in anterior periventricular and centrum semiovale, with decreased FA values in the caudate nucleus, thalamus and centrum semiovale. An increased severity of the WMLs was associated with increased ADC and decreased FA in the NAWM of SIVD patients. After controlling for age, the ADC in the NAWM of the posterior periventricular, NAWM and WMLs in the centrum semiovale, caudate nucleus and thalamus showed significant inverse correlations to MMSE; FA values in NAWM of the anterior periventricular and WMLs of the centrum semiovale were positively correlated to MMSE.</p><p><b>CONCLUSION</b>In SIVD patients, the NAWM and NAGM regions shown by MRI contain diffusion abnormalities, and these abnormalities shown by DTI are significantly correlated to the general cognitive function of the patients.</p>

Proton magnetic resonance spectroscopy of the thalamus and hypothalamus in patients with first-episode depression / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the presence of abnormal metabolism in the thalamus and hypothalamus in patients with first-episode depression.</p><p><b>METHODS</b>Thirty drug-naive patients with first-episode depression and 30 age-matched controls were scanned with proton magnetic resonance spectroscopy ((1)H-MRS) for Naa, Cho, Cr and mI.</p><p><b>RESULTS</b>Compared with the control group, the patients showed significantly reduced mI and mI/Cr of the hypothalamus, reduced mI/Cr of the left thalamus, and lowered Cho, ml, and ml/Cr of the right thalamus (P<0.05).</p><p><b>CONCLUSION</b>Patients with first-episode depression may have myo-inositol and phosphoric acid metabolism disorder in the thalamus and hypothalamus with malfunction of cellular osmotic pressure adjustment mechanism. Abnormal mI/Cr in the thalamus and hypothalamus may represent an important biochemical change in advanced patients with depression.</p>

Intercellular imaging by a polyarginine derived cell penetrating peptide labeled magnetic resonance contrast agent, diethylenetriamine pentaacetic acid gadolinium / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The cellular plasma membrane represents a natural barrier to many exogenous molecules including magnetic resonance (MR) contrast agent. Cell penetrating peptide (CPP) is used to internalize proteins, peptides, and radionuclide. This study was undertaken to assess the value of a new intracellular MR contrast medium, CPP labeled diethylenetriamine pentaacetic acid gadolinium (Gd-DTPA) in molecular imaging in vitro.</p><p><b>METHODS</b>Fluorescein-5-isothiocyanate (FITC) and Gd-DTPA respectively labeled with CPP (FITC-CPP, Gd-DTPA-CPP) were synthesized by the solid-phase method. Human hepatic cancer cell line-HepG2 was respectively stained by FITC-CPP and FITC to observe the uptake and intracellular distribution. HepG2 was respectively incubated with 100 nmol/ml Gd-DTPA-CPP for 0, 10, 30, 60 minutes, and imaged by MR for studying the relationship between the incubation time and T(1)WI signal. The cytotoxicity to NIH3T3 fibroblasts cells was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide reduction assay (MTT).</p><p><b>RESULTS</b>The molecular weights of CPP labeled imaging agents, which were determined by MALDI mass spectrometry (FITC-CPP MW = 2163.34, Gd-DTPA-CPP MW = 2285.99), were similar to the calculated molecular weights. Confocal microscopy suggested HepG2 translocated FITC-CPP in cytoplasm and nucleus independent with the incubation temperature. MR images showed HepG2 uptaken Gd-DTPA-CPP had a higher T(1) weighted imaging (T(1)WI) signal, and that the T(1)WI signal intensity was increasing in a time-dependent manner (r = 0.972, P = 0.001), while the signal intensity between the cells incubated by Gd-DTPA for 60 minutes and the controlled cells was not significantly different (P = 0.225). By MTT, all concentrations from 50 nmol/ml to 200 nmol/ml had no significant (F = 0.006, P = 1.000) effect on cell viability of mouse NIH3T3 fibroblasts, compared with the control group.</p><p><b>CONCLUSIONS</b>The newly constructed CPP based on polyarginine can translocate cells by carrying FITC and MR contrast agent Gd-DTPA, and the intracellular concentrations are readily detectable by MR imaging, suggesting a new way for MR molecular imaging.</p>